1) Field of the Invention
This invention relates to a thin film magnetic head including a slider and a thin film magnetic head element and a method for manufacturing the same.
2) Related Art Statement
In manufacturing of a thin film magnetic head, normally, a first magnetic film (bottom magnetic film), a gap film and a thin film coil separated and supported by an insulating film are formed, and thereafter, a second magnetic film to constitute a top magnetic film is formed. The thin film coil is formed in a constant thickness so as to wind around the backward joining portion (back gap)to join the first magnetic film and the second magnetic film.
In the formation of the second magnetic film, a plate underfilm for the second magnetic film is formed entirely on a wafer including the insulating film by sputtering, etc. Then, a photoresist is applied on the plate underfilm and processed by a photolithography process to form a resistframe having the desired pattern for the second magnetic film. Subsequently, the second magnetic film is formed by electroplating, etc., in the area enclosed by the resistframe.
One of the problems in the manufacturing process of the second magnetic head is that in the photolithography process to form the resistframe, a part of an exposing light is reflected at the insulating film, reaches the area beyond a photomask, and exposes the part of the photoresist except to be defined by the photomask, resulting in the degradation of the pattern precision in the resistframe and the second magnetic film.
The degradation of the pattern precision appears at its pole portion conspicuously. In the pole portion, the second magnetic film is opposed to the first magnetic film via the gap film. The insulating film is located backward from the pole portion, and rises up at a given angle on the gap film with inclination. The start point of the rising up corresponds to a Throat Height zero point and the angle of the rising up corresponds to an Apex Angle.
The part of the second magnetic film up to the Throat Height zero point constitutes the pole portion parallel to the gap film and the first magnetic film, and the remainder is inclined at the Apex Angle toward the upper surface of the insulating film from the Throat Height zero point. Therefore, in forming the resistframe for the second magnetic film by the photolithography, the part of the photoresist stuck on the inclined portion of the insulating film which is inclined at the Apex Angle toward the upper surface of the insulating film from the Throat Height zero point has to be exposed. In this case, since the plate underfilm is stuck on the inclined portion, the exposing light is reflected at the plate underfilm, and then, the part of the exposing light leaves for the pole portion. Accordingly, the exposed pattern of the pole portion differs from the exposing pattern of the photomask, resulting in the pattern deformation of the resistframe.
The pattern deformation is large obstacle for realizing a high density recording through narrowing a recording track width up to 1.0 xcexcm and below.
Kokai publication No. 9-180127 (JP A 9-180127) discloses the technique that before applying a photoresist to constitute a mask for a top magnetic film, an antireflection film is formed, and the photoresist is applied on the antireflection film, exposed and developed, to form a resistframe as a mask for a second magnetic film. After forming the resist frame, the part of the antireflection film exposing to the bottom surface of the opening in the resist frame is removed by an ashing means, etc. and the second magnetic film is formed by plating, etc.
In the above conventional technique, the antireflection film exists entirely within the inner pattern enclosed by the resistframe. The inner pattern of the resistframe has a pole portion area corresponding to the pole portion of the top magnetic film and a second yoke portion corresponding to a yoke portion. The part of the antireflection film in the pole portion area and the second yoke portion area has to be removed.
However, the resistframe has extremely different opening areas for the pole portion area and the second yoke portion. Furthermore, for realizing a high density recording, the opening area of the pole portion is required to be narrowed up to a minute size of 1 xcexcm and below. Consequently, in removing the part of the antireflection film stuck on the inner pattern enclosed by the resistframe, the second yoke portion area has a different etching rate from that of the pole portion area, and the pole portion area requires longer etching time than the second yoke portion. As a result, during the removing of the antireflection film, the resistframe is over-etched to have its too enlarged frame distance. That is, the antireflection which is formed to narrow its pole width enlarges the resistframe distance because it requires the above removing process, which is obstacle for narrowing of the pole width.
It is an object of the present invention to provide a thin film magnetic head having a narrowed recording track width by forming a top magnetic film, particularly its pole portion on an insulating film in a precise pattern without the increase of the electric resistance of a thin film coil entirely.
It is another object of the present invention to provide a method for manufacturing the above thin film magnetic head effectively and precisely.
This invention relates to a thin film magnetic head comprising a slider having an air bearing surface opposing to a magnetic recording medium and an inductive type thin film magnetic head element, provided on the end face of the slider in air outflow side, including a first magnetic film, a second magnetic film, a gap film, and thin film coils,
the first magnetic film having a first pole portion of which forefront is exposed to the air bearing surface and a first yoke portion which extends backward from the air bearing surface,
the second magnetic film having a second pole portion which is opposed to the first pole portion of the first magnetic film and of which forefront is exposed to the air bearing surface and a second yoke portion which extends backward from the air bearing surface and magnetically joined with the first yoke portion of the first magnetic film at a back gap portion,
the gap film being provided at least between the first pole portion of the first magnetic film and the second pole portion of the second magnetic film,
the thin film coils winding around the back gap portion so as to pass through the magnetic circuit enclosed by the first and second magnetic films and being supported by insulating films, wherein
the insulating films to support the thin film coils is provided in between the first and the second yoke portions, and the top thin film coil of the thin film coils has a coil winding body portion with a smaller thickness nearest the air bearing surface than that of a coil winding body portion at the middle between the first and second pole portions and the back gap portion.
In the thin film magnetic head, since the top thin film coil has a coil winding body portion with smaller thickness nearest the air bearing surface than the middle coil winding body portion between the pole portion and the backward joining portion to constitute the back gap portion, the top insulating film may have the thickness distribution that it is thinnest nearest the air bearing surface and thicker at the middle between the pole portion and the backward joining portion. Therefore, the top insulating film to cover the second magnetic head can have a gentle rising inclination angle, and then, the exposed pattern of the photoresist to define the pattern of the resistframe corresponding to the second pole portion can be almost determined by the exposing pattern of the photomask. As a result, the pattern of the resistframe corresponding to the second pole portion can be formed precisely, and thus, the second pole portion can be formed so as to have a precise pattern. Moreover, since the pattern of the resistframe corresponding to the second pole portion can be formed in a precise pattern, the thin film magnetic head having the narrowed recording track width can be manufactured.
Moreover, it is not required that an antireflection film is formed on the insulating film to support the thin film coil. Therefore, the pattern degradation of the resistframe due to the difference in the etching rates between the second yoke portion area and the second pole portion area within the resistframe and the height degradation of the resistframe can be excluded. As a result, the second pole portion and the second yoke portion can be formed in a precise pattern, respectively.
Furthermore, since the thin film coil is thicker at the middle between the pole portion and the backward joining portion, it can have relatively small electric resistance, so that the whole efficiency of the thin film magnetic head can be prevented from being degraded.
In the thin film magnetic head of the present invention, it is preferable that the top thin film coil has a middle coil winding body portion with its maximum thickness between at the middle of the coil winding portion and forward and backward coil winding body portions with gradually declined thickness forward and backward from the middle coil winding body portion. Moreover, the top thin film coil has a smaller lateral cross section width in the thinner coil winding portion than in the thicker coil winding portion. In this invention, the insulating film to support the thin film coil has preferably an inclination angle xcex2 of 20 degrees or below.
This invention also relates to a frame plating method for forming a thin film coil of an inductive type thin film magnetic head comprising the steps of:
forming a plate underfilm on a surface on which a thin film is formed,
forming a resistframe with openings having different opening widths on the plate underfilm, and
growing coil plated films with different thicknesses corresponding to the different opening widths on the plate underfilm.
According to this frame plating method, the coil plated film can be formed thinner at the small opening area (frame distance) of the resistframe and thicker at the large frame distance of the resistframe. Therefore, the thin film coil in the thin film magnetic head of the present invention can be formed easily by selecting the frame distance of the resistframe appropriately. In this case, the above plating method is a direct-current plating method.
This invention further relates to a method for manufacturing a thin film magnetic head comprising a slider having an air bearing surface opposing to a magnetic recording medium and an inductive type thin film magnetic head element, provided on the end face of the slider in air outflow side, including a first magnetic film, a second magnetic film, a gap film, and thin film coils,
the first magnetic film having a first pole portion of which forefront is exposed to the air bearing surface and a first yoke portion which extends backward from the air bearing surface,
the second magnetic film having a second pole portion which is opposed to the first pole portion of the first magnetic film and of which forefront is exposed to the air bearing surface and a second yoke portion which extends backward from the air bearing surface and magnetically joined with the first yoke portion of the first magnetic film at a back gap portion,
the gap film being provided at least between the first pole portion of the first magnetic film and the second pole portion of the second magnetic film,
the thin film coils winding around the back gap portion so as to pass through the magnetic circuit enclosed by the first and second magnetic films and being supported by insulating films, comprising the steps of:
forming a plate underfilm on a surface on which the top thin film coil of the thin film coils is formed,
forming a resistframe with openings having different opening widths corresponding to the thickness of each coil winding body portion to constitute the top thin film coil,
growing plated films to constitute the coil winding body on the plate underfilm via the openings of the resistframe and thereby, obtaining the coil winding body which has smaller thickness nearest the air bearing surface than the middle thereof,
removing the resistframe,
removing the parts of the plate underfilm uncovered with the coil winding body and thereby, forming the top thin film coil, and
forming the second magnetic film by photolithography after forming an insulating film to support the top thin film coil.
According to the above manufacturing method of a thin film magnetic head, the coil winding body to constitute the thin film coil can be formed by the direct-current plating method. Moreover, it is preferable that the resistframe has the opening with its maximum lateral cross section width at the middle between the pole portion and the back gap portion and the openings with their gradually declined lateral cross section width forward and backward from the middle.
The manufacturing method of the present invention may be applied for various types of thin film magnetic head. For example, a self-alignment type (hereinafter, called as a xe2x80x9cSA typexe2x80x9d) thin film magnetic head as well as a normal thin film magnetic head can be formed by the manufacturing method. The insulating film includes a first insulating film and a second insulating film. The first insulating film supports the thin film coil. The second insulating film is provided at the base portion of the first insulating film in the air bearing surface side, and determines its Throat Height zero point.